Can We Reverse Cognitive Decline?

A recent study by French researcher Isabelle Mosnier, of Assistance Publique-Hopitaux de Paris, found that cognitive decline in elderly people with hearing loss could be reversed by giving patients cochlear implants, followed by intensive speech-language therapy.

Mosnier studied 94 patients, aged 65 to 85. All had severe to profound hearing loss in at least one ear. We know from previous studies that hearing loss and cognitive decline are statistically associated. The worse the hearing loss, the more likely and more severe the cognitive decline, including dementia.

What Mosnier's study showed was that in the patients with the most severe cognitive impairment, cochlear implants and speech therapy actually reversed the loss. The implants and/or therapy also lessened depression. Not surprisingly, they also improved speech perception in both quiet and noisy settings.

The study, published in the journal JAMA Otolaryngology-Head & Neck Surgery, is important because it is the first to measure the effect of cochlear implants on memory and mental flexibility in elderly patients.

Cochear implant surgery is often not considered for elderly patients with severe hearing loss. This has partly to do with our dismissive attitude towards hearing loss as just a natural condition of aging. But the surgery is very successful in the elderly, well into their 90's, and can make an enormus difference in quality of life.

For more on this study see "Cochlear Implants Shown to Reverse Cognitive Decline."

P. Murali Doraiswamy, M.D., a professor of psychiatry and medicine at Duke University and co-author of The Alzheimer’s Action Plan, calls the study “a definite wake-up call.” Although he says the study had some shortcomings, “the improvement in cognition was huge—about double that seen with any of the current FDA drugs for treating Alzheimer’s.” He adds that the findings about hearing loss affecting cognitive tests probably apply to other senses like vision, smell and touch. For example: “Studies have shown that uncorrected vision problems raise the risk for dementia,” he says.

While the link between hearing loss and milder cognitive problems has been questioned by some, it is becoming increasingly accepted. “Every doctor knows that hearing loss can result in cognitive problems, but they still don’t focus on it as a priority when they evaluate someone with suspected dementia—which is a big missed opportunity,” says Doraiswamy. “We need long-term controlled trials looking at whether cochlear implants can delay the onset of dementia in at-risk subjects, which will clinch the case.”

The implications of the study have global relevance: “Our study demonstrated that hearing rehabilitation using cochlear implants in the elderly is associated with improvements in impaired cognitive function,” Mosnier wrote. “Given the projection of an increase to more than 100 million people with dementia worldwide by 2050, any study that suggests a way to offset that decline, even temporarily, has enormous public-health significance.”